1. Field of the Invention
The present invention relates to an organic electroluminescence (EL) panel comprising, on a substrate, organic EL elements arranged in a matrix and a plurality of thin film transistors for driving the organic EL elements, in which a sealing panel is bonded to the peripheral portion of the substrate for sealing the area above the pixel region where the organic EL elements are provided.
2. Description of Related Art
Organic EL display panels (organic EL display panels) have conventionally been known as one example of flat display panels. Because, unlike liquid crystal display (LCD) panels, organic EL display panels are self emissive and because organic EL display panels are bright and clear flat display panels, their widespread use is very much expected.
An organic EL display panel comprises a large number of organic EL elements arranged in a matrix, and employs these organic EL elements as pixels of a display. Such organic EL elements can be driven passively or actively, similar to LCDs, and, as is also the case with LCDS, active matrix displays are more preferable. More specifically, in active matrix displays, switching elements (typically two elements including a switching element and a driving element) are provided for each pixel and display of each pixel is controlled by controlling the switching elements, whereas in passive driving, a switching element is not provided for each pixel. Of these two types of displays, the active matrix is more preferable because much more precise displays can be achieved.
The organic EL element emits light when current flows through an organic emissive layer. In many cases, a hole transport layer and an electron transport layer formed of an organic material are provided adjacent to the organic emissive layer, in order to assist the light emission. These organic layers, however, suffer from a problem of deterioration when exposed to moisture.
To deal with the above problem, in an organic EL display, the area above the display region where the organic EL element is provided is covered with a cathode formed of a metal, and the space above the display region (a region where a pixel is disposed) is made airtight and a drying agent placed in the airtight space, thereby removing moisture.
However, such a conventional organic EL display panel often does not have a sufficiently long life. In this regard, our study has revealed that the space above the organic EL element is often not sufficiently dry, namely that effective prevention of intrusion of external moisture is not sufficiently performed in that space.